Film formation apparatus, method for forming film, and method for manufacturing photoelectric conversion device

ABSTRACT

The present invention relates to a film formation apparatus including a first transfer chamber having a roller for sending a substrate, a film formation chamber having a discharging electrode, a buffer chamber provided between the transfer chamber and the film formation chamber or between the film formation chambers, a slit provided in a portion where the substrate comes in and out in the buffer chamber, and a second transfer chamber having a roller for rewinding the substrate. The slit is provided with at least one touch roller, and the touch roller is in contact with a film formation surface of the substrate. In addition, the present invention also relates to a method for forming a film and a method for manufacturing a photoelectric conversion device that are performed by using such a film formation apparatus.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a photoelectric conversion element, aphotoelectric conversion device, and a method for manufacturing thesame. Further, the present invention also relates to an electronicappliance and a semiconductor device using a photoelectric conversiondevice.

2. Description of the Related Art

In recent years, a process in which a photoelectric conversion devicecan be manufactured at low cost has been expected. As one of methods forattempting low cost manufacture, a method has been known, by which eachunit operation such as film formation, printing, or laser processing iscontinuously processed in a process where a rolled flexible substrate isrewound to another roll. This method is referred to as a Roll-to-Rollmethod (refer to Patent Document 1: Japanese Published PatentApplication No. 2001-223375).

FIGS. 2A and 2B show a film formation apparatus for a conventionalRoll-to-Roll method. A film formation apparatus of FIGS. 2A and 2Binclude a plurality of chambers, for example, a film formation chamber1001, and buffer chambers 1002 (1002 a and 1002 b). In the filmformation chamber 1001, a discharging electrode 1011 is provided. Ineach of the buffer chambers 1002 a and 1002 b, touch rollers 1012 (1012a and 1012 b) are respectively provided. Slits 1013 (1013 a, 1013 b,1013 c, and 1013 d) are respectively formed between a transfer chamber1005 and the buffer chamber 1002 a, between the buffer chamber 1002 aand the film formation chamber 1001, between the film formation chamber1001 and the buffer chamber 1002 b, and between the buffer chamber 1002b and a transfer chamber 1006. In other words, the slit 1013 b isprovided between the film formation camber 1001 and the buffer chamber1002 a, and the slit 1013 c is provided between the film formationchamber 1001 and the buffer chamber 1002 b. Each slit is provided withtouch rollers 1014 (1014 a, 1014 b, 1014 c, 1014 d, 1014 e, 1014 f, 1014g, and 1014 h). In other words, the slit 1013 a is provided with thetouch rollers 1014 a and 1014 b, the slit 1013 b is provided with thetouch rollers 1014 c and 1014 d, the slit 1013 c is provided with thetouch rollers 1014 e and 1014 f, and the slit 1013 d is provided withthe touch rollers 1014 g and 1014 h.

A substrate 1018 that is sent from a roller (also called a bobbin) 1015passes through each of the touch rollers 1012 and 1013 and thedischarging electrode 1011, and then, is rewound by a roller 1016. Afilm is formed over the substrate 1018 between the dischargingelectrodes 1011 provided in the film formation chamber 1001.

However, in the conventional film formation apparatus of FIGS. 2A and2B, there was possibility that the substrate 1018 is curled in passingthrough the touch rollers, in other words, a phenomenon occurs, in whichthe substrate 1018 is turned up toward a surface where a film is notformed (a rear surface). When the substrate 1018 is curled, aphotoelectric conversion device may be difficult to be used as a productand a yield may be reduced.

Further, if the rear surface of the substrate 1018 is damaged by thetouch rollers, light to be received may have adverse effect, orappearance quality may be deteriorated in being incorporated into aproduct.

SUMMARY OF THE INVENTION

It is an object of the present invention to suppress occurrence of acurled substrate in film formation and provide a highly reliablephotoelectric conversion device by suppressing occurrence of damage in alight receiving region, thereby obtaining a photoelectric conversiondevice with high reliability.

According to one feature of the present invention, a film formationapparatus includes a first transfer chamber having a roller for sendinga substrate, a film formation chamber having a discharging electrode, abuffer chamber provided between the transfer chamber and the filmformation chamber or between the film formation chambers, a slitprovided in a portion where the substrate comes in and out in the bufferchamber, and a second transfer chamber having a roller for rewinding asubstrate; the slit is provided with at least one touch roller; and thetouch roller is in contact with a film formation surface (a surface onwhich a film is formed) of the substrate.

According to one feature of the present invention, a method for forminga film includes the steps of sending a substrate from a roller forsending a substrate, which is provided in a first transfer chamber;forming a film over the substrate by making the substrate pass through adischarging electrode provided in a film formation chamber; transferringthe substrate through a slit provided in a buffer chamber that isprovided between the transfer chamber and the film formation chamber orbetween the film formation chambers; and rewinding the substrate overwhich the film is formed by a roller for rewinding a substrate, which isprovided in a second transfer chamber. The slit is provided with atleast one touch roller, and the touch roller is in contact with asurface of the substrate over which the film is formed.

In the present invention, the second transfer chamber is provided with aroller for sending a protective sheet (also referred to as a “protectivefilm”); and the protective sheet is sent to be in contact with a filmformation surface of the substrate and rewound together with thesubstrate by the roller for rewinding a substrate.

In the present invention, the discharging electrodes are composed of anupper electrode and a lower electrode, the upper electrode is formed ofa plurality of parts, and insulators are formed between the plurality ofparts of the upper electrode.

In the present invention, the film may be a semiconductor film, and thesemiconductor film may be any one of a silicon film, a germanium film,and a silicon film containing germanium.

According to one feature of the present invention, a method formanufacturing a photoelectric conversion device includes the steps ofsending a substrate from a roller for sending a substrate, which isprovided in a first transfer chamber; forming a first semiconductor filmover the substrate by making the substrate pass through firstdischarging electrodes provided in a first film formation chamber;transferring the substrate over which the first semiconductor film isformed through a first slit provided in a first buffer chamber; forminga second semiconductor film over the first semiconductor film by makingthe substrate pass through second discharging electrodes provided in asecond film formation chamber; transferring the substrate over which thesecond semiconductor film is formed through a second slit provided in asecond buffer chamber; forming a third semiconductor film havingopposite conductivity to the first semiconductor film over the secondsemiconductor film by making the substrate pass through thirddischarging electrodes provided in a third film formation chamber; andrewinding the substrate over which the first to third semiconductorfilms are formed by a roller for rewinding a substrate, which isprovided in a second transfer chamber. Each of the first slit and thesecond slit is provided with at least one touch roller, and the touchroller is in contact with a surface of the substrate over which thesemiconductor film is formed.

In the present invention, the second transfer chamber is provided with aroller for sending a protective sheet, and the protective sheet is sentto be in contact with a surface over which the third semiconductor filmis formed and rewound together with the substrate by a roller forrewinding a substrate.

In the present invention, the protective sheet may be a paper, a metalfoil, or an organic film.

In the present invention, the second discharging electrodes are composedof an upper electrode and a lower electrode, the upper electrode isformed of a plurality of parts, and insulators are formed between theplurality of parts of the upper electrode

In the present invention, the substrate may be any one of a polyethylenenaphthalate (PEN) film, a polyethylene terephthalate (PET) film, and apolybutylene naphthalate (PBN) film.

In the present invention, each of the first to third semiconductor filmsmay be any one of a silicon film, a germanium film, and a silicon filmcontaining germanium.

In the present invention, the photoelectric conversion device may be asolar battery.

In the present invention, the photoelectric conversion device may be aphotosensor.

In the present specification, a photoelectric conversion layer is alayer having a structure that is necessary for converting light energyinto electric energy. For example, semiconductor layers of stackedp-type, i-type, and n-type films, semiconductor layers having a PNjunction, or the like can be given. Further, when a semiconductor layerhas a PIN structure, an intrinsic layer is a region where a carriercontributing to photoelectromotive force is generated. When asemiconductor layer has a PN junction, a depletion layer in a PNjunction interface is a region where a carrier contributing tophotoelectromotive force is generated. In other words, electrodes areconnected to both edges of a photoelectric conversion layer, and thephotoelectric conversion layer is irradiated with light; accordingly,photoelectromotive force can be extracted from the electrodes.

In the present specification, a photoelectric conversion element is anelement having a photoelectric conversion layer, and a photoelectricconversion device is a device having one or a plurality of photoelectricconversion elements.

In the present specification, a semiconductor device indicates generaldevices capable of functioning by utilizing a semiconductorcharacteristic, and a photoelectric conversion device, a semiconductorcircuit, an electrooptical device and an electronic appliance each ofwhich has a semiconductor layer are all semiconductor devices.

In the present invention, a film is formed over a surface opposite to alight receiving region over a substrate so that a touch roller is incontact with a film formation surface. Thus, damage to the lightreceiving region of an element can be prevented. Therefore, a highlyreliable photoelectric conversion device can be obtained.

In accordance with the present invention, occurrence of curl can besuppressed in a boundary between a region where a film is formed and aregion where a film is not formed. Thus, damage to a light receivingregion of an element can be prevented.

In accordance with the present invention, curling of a substrate can besuppressed, so that a substrate can be transferred smoothly. Therefore,a film formation apparatus having high stability for transfer can beobtained.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A to 1C are views showing a film formation apparatus of thepresent invention;

FIGS. 2A and 2B are views showing a conventional film formationapparatus;

FIG. 3 is a view showing a film formation apparatus of the presentinvention;

FIGS. 4A to 4C are views showing a film formation apparatus of thepresent invention;

FIGS. 5A and 5B are views showing a film formation apparatus of thepresent invention;

FIG. 6 is a view showing a film formation apparatus of the presentinvention;

FIG. 7 is a view showing a film formation apparatus of the presentinvention;

FIGS. 8A to 8C are views showing a process for manufacturing aphotoelectric conversion device of the present invention;

FIGS. 9A to 9C are views showing a process for manufacturing aphotoelectric conversion device of the present invention;

FIG. 10 is a top view of a photoelectric conversion device of thepresent invention;

FIGS. 11A to 11C are cross-sectional views of a photoelectric conversiondevice of the present invention;

FIG. 12 is a cross-sectional view of a photoelectric conversion deviceof the present invention;

FIGS. 13A and 13B are views showing a device on which a photoelectricconversion device of the present invention is mounted;

FIGS. 14A and 14B are views showing a process for manufacturing aphotoelectric conversion device of the present invention;

FIGS. 15A to 15C are views showing a process for manufacturing aphotoelectric conversion device of the present invention;

FIGS. 16A and 16B are views showing a process for manufacturing aphotoelectric conversion device of the present invention;

FIGS. 17A and 17B are views showing a process for manufacturing aphotoelectric conversion device of the present invention;

FIG. 18 is a view showing a process for manufacturing a photoelectricconversion device of the present invention;

FIGS. 19A to 19D are views showing a process for manufacturing aphotoelectric conversion device of the present invention;

FIGS. 20A to 20D are views showing a process for manufacturing aphotoelectric conversion device of the present invention;

FIGS. 21A to 21C are views showing a process for manufacturing aphotoelectric conversion device of the present invention;

FIGS. 22A to 22C are views showing a process for manufacturing aphotoelectric conversion device of the present invention;

FIG. 23 is a view showing a process for manufacturing a photoelectricconversion device of the present invention;

FIG. 24 is a circuit diagram of a photoelectric conversion device of thepresent invention;

FIG. 25 is a circuit diagram of a photoelectric conversion device of thepresent invention;

FIG. 26 is a circuit diagram of a photoelectric conversion device of thepresent invention;

FIG. 27 is a view showing a device on which a photoelectric conversiondevice of the present invention is mounted;

FIGS. 28A and 28B are views showing a device on which a photoelectricconversion device of the present invention is mounted;

FIGS. 29A and 29B are views showing a device on which a photoelectricconversion device of the present invention is mounted;

FIG. 30 is a view showing a device on which a photoelectric conversiondevice of the present invention is mounted; and

FIGS. 31A and 31B are views showing a device on which a photoelectricconversion device of the present invention is mounted.

DETAILED DESCRIPTION OF THE INVENTION

Embodiment Modes of the present invention will be explained in detailwith reference to drawings. However, the present invention is notlimited to the following explanation and is easily understood by thoseskilled in the art that various changes and modifications are possible,unless such changes and modifications depart from the content and thescope of the invention. Therefore, the present invention is notconstrued as being limited to descriptions of the following EmbodimentModes. It is to be noted that, in structures of the present inventionexplained below, reference numeral denoting the same portion is used incommon among different drawings.

Embodiment Mode 1

This embodiment mode will be explained with reference to FIGS. 1A to 1C,FIG. 3, FIGS. 4A to 4C, and FIGS. 5A and 5B.

FIG. 1A shows an overall view of a film formation apparatus of thisembodiment mode, and FIGS. 1B and 1C show views of an enlarged slit andtouch roller. The film formation apparatus shown in FIG. 1A includestransfer chambers 101 and 106, buffer chambers 102 (102 a, 102 b, and102 c), and film formation chambers 103, 104, and 105.

In the transfer chamber 101, a roller 111 and a touch roller 112 forsending a substrate 121 are provided. The substrate 121 is a flexiblesubstrate, and for example, a polyethylene naphthalate (PEN) film, apolyethylene terephthalate (PET) film, a polybutylene naphthalate (PBN)film, or the like may be used. The substrate 121 is sent from the roller111 to the buffer chamber 102.

The buffer chamber 102 is provided between the transfer chamber and thefilm formation chamber or between the film formation chambers. Bytransferring a substrate to the film formation chamber through thebuffer chamber, each film can be formed in separate film formationchambers.

In portions where the substrate 121 comes in and out in the bufferchamber 102, a slit 113 is provided. Each slit 113 (113 a, 113 b, 113 c,113 d, 113 e, 113 f, and 113 g) is provided with a touch roller 114 (114a, 114 b, 114 c, 114 d, 114 e, 114 f, and 114 g). In other words, theslits 113 a and 113 b are provided to the buffer chamber 102 a, and theslits 113 a and 113 b are respectively provided with the touch rollers114 a and 114 b. Further, the slits 113 c and 113 d are provided to thebuffer chamber 102 b, and the slits 113 c and 113 d are respectivelyprovided with the touch rollers 114 c and 114 d. The slits 113 e and 113f are provided to the buffer chamber 102 c, and the slits 113 e and 113f are respectively provided with the touch rollers 114 e and 114 f.

Further, the slit 113 g is provided between the film formation chamber105 and the transfer chamber 106, and the slit 113 g is provided withthe touch roller 114 g.

FIG. 1B shows an enlarged view of the slit 113 d provided between thebuffer chamber 102 b and the film formation chamber 104 and the touchroller 114 d. Other slits and touch rollers have the same structure asthe slit 113 d and the touch roller 114 d. The substrate 121 is incontact with the touch roller 114 d when passing through the slit 113 d.A film is formed on a surface of the substrate 121, which is in contactwith the touch roller 114 d. The touch roller 114 d is in contact withonly an edge portion of a film formation surface of the substrate 121. Alight receiving region of an element is mainly a surface opposite to thefilm formation surface of the substrate 121; therefore, the touch rolleris in contact with the film formation surface, whereby damage to thelight receiving region of an element can be prevented.

In FIGS. 1A and 1B, one touch roller is provided for each slit. However,the number of the touch rollers is not necessary to be one slit foreach, and two or more touch rollers may be provided if necessary as longas a film formation surface is not damaged. For example, two touchrollers 114 d and 114 d′ may be provided for the slit 113 d as shown inFIG. 1C. Alternatively, the number of the touch rollers may be changeddepending on a slit. For example, one touch roller may be provided forone slit, and plural touch rollers, e.g., two touch rollers may beprovided for another slit.

In each of the film formation chambers 103, 104, and 105, asemiconductor film may be formed by a plasma CVD method. In thisembodiment mode, the film formation chamber 103 is provided with adischarging electrode 115. When the substrate 121 passes through thedischarging electrodes 115, a first semiconductor film, which is ap-type semiconductor film in this embodiment mode, is formed. As thep-type semiconductor film, a semiconductor film containing an impurityelement belonging to Group 13 of the periodic table, for example, boron(B), more specifically, a p-type amorphous silicon film may be formed.

Further, instead of silicon, germanium or silicon containing germanium(silicon germanium) may be used. Instead of an amorphous semiconductorfilm, a semiamorphous semiconductor film may be used.

It is to be noted that a semiamorphous semiconductor film indicates afilm including a semiconductor that has an intermediate structurebetween an amorphous semiconductor and a semiconductor having acrystalline structure (including single crystal and polycrystal). Thesemiamorphous semiconductor film is a semiconductor film having a thirdcondition that is stable in term of free energy and is a crystallinesubstance having a short-range order and lattice distortion. A crystalgrain thereof can be dispersed in the non-single crystallinesemiconductor film by setting a grain size thereof to be 0.5 to 20 nm.Raman spectrum thereof is shifted toward lower wave number side than 520cm⁻¹. The diffraction peaks of (111) and (220), which are considered tobe derived from a Si crystal lattice, are observed in the semiamorphoussemiconductor film by X-ray diffraction. The semiamorphous semiconductorfilm contains at least 1 atomic % or more of hydrogen or halogen as amaterial for terminating a dangling bond. In this specification, such asemiconductor film is referred to as a semiamorphous semiconductor (SAS)film for the sake of convenience. The lattice distortion is furtherextended by including a rare gas element such as helium, argon, krypton,and neon so that a favorable semiamorphous semiconductor film withimproved stability can be obtained. It is to be noted that amicrocrystalline semiconductor film is also included in a semiamorphoussemiconductor film.

An SAS film can be obtained by glow discharge decomposition of a gascontaining silicon. SiH₄ is a typical gas containing silicon, andadditionally, Si₂H₆, SiH₂Cl₂, SiHCl₃, SiCl₄, SiF₄, or the like can beused. An SAS film can be easily formed by using the gas containingsilicon diluted with hydrogen or gas in which one or more of rare gaselements selected from helium, argon, krypton, and neon are added tohydrogen. The gas containing silicon is preferably diluted with adilution ratio in a range of twice to 1000 times. In addition, a carbidegas such as CH₄ or C₂H₆; a germanide gas such as GeH₄ and GeF₄; F₂; andthe like may be mixed into the gas containing silicon to adjust thewidth of an energy band at 1.5 to 2.4 eV or 0.9 to 1.1 eV.

The film formation chamber 104 is provided with discharging electrodes116, 117, and 118. In the film formation chamber 104, an i-typesemiconductor film (also referred to as an “intrinsic semiconductorfilm”) as a second semiconductor film is formed. Since the i-typesemiconductor film is often formed to be thick, three dischargingelectrodes are provided. A discharging electrode which is three timeslarger than the area may be formed; however, there is a possibility thatelectric power to be supplied becomes unstable, and film quality of aformed film becomes ununiform due to an ununiform generated voltage.Therefore, by separating the electrode, a film having further higherquality can be obtained.

Although three discharging electrodes 116 to 118 are used for forming ani-type semiconductor film in this embodiment mode, it is needless to saythat the number of the discharging electrodes is not limited thereto.Two discharging electrodes may be provided, and also four or moredischarging electrodes may be provided. Further, one dischargingelectrode is sufficient as long as stable electric power can besupplied.

It is to be noted that the i-type semiconductor film may be any one ofan i-type amorphous silicon film, an i-type amorphous germanium film, ani-type amorphous silicon germanium film, an i-type semiamorphous siliconfilm, an i-type semiamorphous germanium film, and an i-typesemiamorphous silicon germanium film.

In the present specification, the i-type semiconductor film indicates asemiconductor film in which an impurity imparting p-type or n-typeconductivity has a concentration of 1×10²⁰ cm⁻³ or less, oxygen andnitrogen each have a concentration of 5×10¹⁹ cm⁻³ or less, andphotoconductivity of 1000 times or more with respect to darkconductivity is included. Further, an element belonging to Group 13 of aperiodic table, for example, boron (B) of 10 to 1000 ppm, may be addedto the i-type semiconductor film.

The film formation chamber 105 is provided with a discharging electrode119. In the film formation chamber 105, a third semiconductor filmhaving opposite conductivity to that of the first semiconductor film,which is an n-type semiconductor film in this embodiment mode, isformed. As an n-type semiconductor film, a semiconductor film containingan impurity element belonging to Group 15 of a periodic table, forexample phosphorus (P) may be formed.

Further, in the same manner as the i-type semiconductor film, an n-typesemiconductor film may be any one of an n-type amorphous silicon film,an n-type amorphous germanium film, an n-type amorphous silicongermanium film, an n-type semiamorphous silicon film, an n-typesemiamorphous germanium film, and an n-type semiamorphous silicongermanium film.

Although a p-type semiconductor film, an i-type semiconductor film, andan n-type semiconductor film are stacked in this order in thisembodiment mode, a p-type semiconductor film and an n-type semiconductorfilm may be stacked in a reverse order. In other words, an n-typesemiconductor film, an i-type semiconductor film, and a p-typesemiconductor film may be stacked in this order.

The transfer chamber 106 is provided with a roller 120 for rewinding asubstrate and a roller 125. A protective sheet 122 is sent to be incontact with the film formation surface of the substrate 121 from theroller 125, and is rewound together with the substrate 121 by the roller120.

The protective sheet 122 is formed of, for example, paper, metal foil,an organic film, or the like. When the substrate 121 is rewound by theroller 120, the substrate 121 can be rewound so that the film formationsurface of the substrate 121 is not in contact with a rear surfacethereof.

Dust is attached to the rear surface of the substrate 121 in a processof the film formation. If the substrate 121 is directly rewound to theroller 120 with dust, the film formation surface is damaged. Therefore,it is effective for protecting the film formation surface to rewind theprotective sheet 122 so as to be in contact with the film formationsurface together with the substrate 121 to the roller 120.

The numbers of buffer chambers, film formation chambers, touch rollers,slits, and discharging electrodes are not limited to this embodimentmode. It is needless to say that the numbers thereof may be changed asneeded.

The substrate 121 is bent by self-weight in a process of transferringthe substrate 121. Therefore, the touch roller, the slit, thedischarging electrode, and the like may be provided by changing a heightthereof from a floor or ceiling of a device depending on bending of thesubstrate as shown in FIG. 1A.

Here, a detailed structure of the discharging electrodes 115 to 119 areshown in FIG. 3, FIGS. 4A to 4C, and FIGS. 5A and 5B.

Each of the discharging electrodes 115 to 119 includes an upperelectrode 201, roll electrodes 203 (203 a, 203 b, 203 c, 203 d, 203; and203 f), and a lower electrode 202.

The roll electrodes 203 a to 203 f are arranged along the bending of thesubstrate 121.

The lower electrode 202 has a hollow structure, and vents 206 of gas areformed on a surface of the lower electrode. Such an electrode isreferred to as a shower electrode in the present specification. Amaterial gas necessary for film formation gushes from this vent 206, andis decomposed by plasma generated between the upper electrode 201 andthe roll electrode 203, and the lower electrode 202. In such a manner, afilm is formed on a surface (a lower surface in FIG. 3) of the substrate121.

A mask 204 for preventing a plasma space from expanding may be providedbetween the substrate 121 and the lower electrode 202 as needed.

Here, length of the roll electrode 203 is set to be d₁. Length of thelower electrode 202 in a perpendicular direction to a direction oftransferring the substrate 121, in other words, length in a longitudinaldirection of the lower electrode is set to be d₂. Length of an opening205 in the mask 204 in a perpendicular direction to a direction oftransferring the substrate 121, in other words, length in a longitudinaldirection of the opening 205 in the mask 204 is set to be d₃. Width ofthe substrate 121 is set to be d₄. When the above conditions areemployed, it is preferable to satisfy a relation of Formula 1.d₁>d₃>d₄  [Formula 1]

In a case where the length d₃ in a longitudinal direction of the opening205 in the mask 204 is set to be shorter than the width d₄ of thesubstrate 121 (that is, in a case of d₃<d₄), an edge portion of thesubstrate 121 has a region where a film is formed (a film formationregion) and a region where a film is not formed (a non-film formationregion). Curling occurs in a boundary between the film formation regionand the non-film formation region, and then, the substrate may be turnedup. Therefore, there is a possibility that problems occur in subsequentprocesses. Thus, it is preferable to satisfy Formula 1 in a case ofproviding the mask 204.

Alternatively, in a case of not providing the mask 204, it is preferableto satisfy a relation of Formula 2.d₁>d₂>d₄  [Formula 2]

If the mask 204 is not provided, in a case where the length d₂ in alongitudinal direction of the lower electrode 202 is set to be shorterthan the width d₄ of the substrate 121 (that is, in a case of d₂<d₄),the substrate 121 is protruded from the lower electrode 202, and an edgeportion of the substrate 121 has a region where a film is formed and aregion where a film is not formed. Therefore, in order to preventoccurrence of curling as the same as the case of providing the mask 204,it is preferable to satisfy Formula 2 in a case of not providing themask 204.

Embodiment Mode 2

In this embodiment mode, an example of a different structure of the filmformation chamber 104 in FIGS. 1A to 1C from that of Embodiment Mode 1will be explained with reference to FIG. 6 and FIG. 7.

FIG. 6 shows a state in which a substrate 121 is transferred betweenupper electrodes 301 (301 a, 301 b, and 301 c) and lower electrodes 302(302 a, 302 b, and 302 c) of a discharging electrode provided in a filmformation chamber. Masks 304 (304 a, 304 b, and 304 c) are providedbetween the substrate 121 and the lower electrodes 302. In other words,the lower electrode 302 a is provided with the mask 304 a, the lowerelectrode 302 b is provided with the mask 304 b, and the lower electrode302 c is provided with the mask 304 c.

The upper electrode 301 is divided into a plurality of upper electrodes,for example, three upper electrodes 301 a, 301 b, and 301 c, each ofwhich has a roll electrode 303. In other words, the upper electrode 301a is provided with the roll electrodes 303 a (303 aa, 303 ab, 303 ac,303 ad, and 303 ae), the upper electrode 301 b is provided with the rollelectrodes 303 b (303 ba, 303 bb, 303 bc, and 303 bd), and the upperelectrode 301 c is provided with the roll electrodes 303 c (303 ca, 303cb, 303 cc, and 303 cd).

Insulators 311 (311 a and 311 b) are formed between the upper electrodes301. In other words, the insulator 311 a is formed between the upperelectrodes 301 a and 301 b, and the insulator 311 b is formed betweenthe upper electrodes 301 b and 301 c.

By forming the insulators 311, a plasma space can be surrounded. If theinsulator 311 is not formed, the upper electrodes 301 become one largeelectrode and electric power that is shared at one time becomes large,which is not preferable. Further, the plasma space may become large andunstable; therefore, there is a possibility of adverse effect on filmformation.

In addition, a heater 307 may be provided inside each of the upperelectrodes 301. FIG. 7 shows an example in which a heater is provided inthe upper electrode 301 a. Heaters 307 aa to 307 ae are provided betweenor next to the roll electrodes 303 aa to 303 ae. By providing theheaters 307, a temperature can be uniformed, and then, further stableplasma can be generated.

It is needless to say that the number of upper electrodes, rollelectrodes, lower electrodes, insulators, and heaters is not limited tothis embodiment mode, and the number thereof may be changed as needed.

In this embodiment mode, the film formation chamber 104 of EmbodimentMode 1, that is, a film formation chamber forming an i-typesemiconductor film, is described. However, a film formation chamberforming a p-type semiconductor film and a film formation chamber formingan n-type semiconductor film may have the same structure, if necessary.

It is to be noted that this embodiment mode can be combined with anydescription in Embodiment Mode 1, if necessary.

Embodiment 1

In this embodiment, a method for manufacturing a solar battery by thepresent invention will be explained with reference to FIGS. 5A to 5C,FIGS. 9A to 9C, FIG. 10, FIGS. 11A to 11C, FIG. 12, and FIGS. 13A and13B.

In FIG. 8A, as for a substrate 401, an organic resin material such aspolyethylene terephthalate (PET), polyethylene naphthalate (PEN),polyether sulfone (PES), or polybutylene naphthalate (PBN) is used. Inthis embodiment, polyethylene naphthalate (PEN) with a thickness of 60to 100 μm is used as the substrate 401.

A solar battery manufactured in this embodiment is an integrated solarbattery in which a plurality of unit cells is connected in series overthe same substrate. Further, the solar battery of this embodiment has astructure in which light is received in a surface opposed to a surfaceover which a photoelectric conversion layer is formed over the substrate401. A transparent electrode layer 402 is first formed over thesubstrate 401. The transparent electrode layer 402 is formed from indiumtin oxide alloy (also referred to as indium tin oxide (ITO)), zinc oxide(ZnO), tin oxide (SnO₂), ITO—ZnO alloy, or the like to have a thicknessof 40 to 200 nm (preferably, 50 to 100 nm). Since a continuously usablemaximum temperature of the above organic risen material is 200° C. orless, the transparent electrode layer 402 is formed by a sputteringmethod, a vacuum evaporation method, or the like, and the film formationis performed while the substrate temperature is limited within the rangefrom a room temperature to approximately 150° C. Detailed manufacturingconditions may be appropriately determined by an operator to obtainsheet resistance of 20 to 200 Ω/square for the above film thickness.

In terms of lowering resistance of the transparent electrode layer 402,an ITO film is suitable. However, if an ITO film is exposed to a plasmaatmosphere containing hydrogen in a case of forming a semiconductorlayer thereover, a light transmitting property of the ITO film isdeteriorated because of reduction. In order to prevent this, it ispreferable that a SnO₂ film or a ZnO film be formed over the ITO film.The ZnO (ZnO:Ga) film containing gallium (Ga) of 1 to 10 wt % has a hightransmittance and is suitable to be stacked over the ITO film. As anexample of a combination thereof, when the ITO film is formed to have athickness of 50 to 60 nm and the ZnO:Ga film is formed thereover to havea thickness of 25 nm, it is possible to prevent a light transmittingproperty from being deteriorated, and a favorable light transmittingproperty can be obtained. In this stacked film, sheet resistance of 120to 150 Ω/square can be obtained.

A non-single crystalline semiconductor film that is formed by using afilm formation apparatus of the present invention is formed as aphotoelectric conversion layer 405 over the transparent electrode layer402. The film formation apparatus of the present invention is describedin detail in Embodiment Modes 1 and 2; therefore, it is omitted here.Typically, the photoelectric conversion layer 405 is formed of ahydrogenated amorphous silicon (a-Si:H) film manufactured using a SiH₄gas as a raw material. Besides, a hydrogenated amorphoussilicon-germanium (a-SiGe:H) film, a hydrogenated amorphoussilicon-carbon (a-SiC:H) film, a hydrogenated microcrystalline silicon(μc-Si:H) film, or the like is used. The photoelectric conversion layer405 has a structure in which a first semiconductor layer, a secondsemiconductor layer, and a third semiconductor layer having oppositeconductivity to the first semiconductor layer are formed by a PINjunction. In the photoelectric conversion layer 405, p-type and n-typelayers with valence electron control may be formed by using a-Si:H orμc-Si:H to which a p-type impurity (such as boron) or an n-type impurity(such as phosphorus or arsenic) is added. Especially, μc-Si:H issuitable for the purpose of lowering light absorption loss or makingfavorable ohmic contact with the transparent electrode or a rear surfaceelectrode.

In the photoelectric conversion layer 405, as the first semiconductorlayer, the second semiconductor layer, and the third semiconductorlayer, a p-type semiconductor layer, an intrinsic semiconductor layer(also referred to as an “i-type semiconductor layer”), and an n-typesemiconductor layer may be stacked in this order. Alternatively, ann-type semiconductor layer, an i-type semiconductor layer, and a p-typesemiconductor layer may be stacked in this order. FIG. 8B shows a statein which a p-type semiconductor layer 405 p, an i-type semiconductorlayer 405 i, and an n-type semiconductor layer 405 n are stacked in thisorder from a transparent electrode layer 402 side as the photoelectricconversion layer 405. The p-type semiconductor layer 405 p, the i-typesemiconductor layer 405 i, and the n-type semiconductor layer 405 nrespectively have a thickness of 10 to 20 nm, 200 to 1000 nm, and 20 to60 nm. When a PIN junction is formed of such a non-single crystalsilicon material, an open circuit voltage of approximately 0.4 to 1 Vcan be obtained. If this PIN junction is assumed to be one unit and aplurality of such units are stacked to form a stack type structure, theopen circuit voltage can also be raised.

In the present specification, an i-type semiconductor layer indicates asemiconductor layer in which an impurity imparting p-type or n-typeconductivity has a concentration of 1×10²⁰ cm³ or less, oxygen andnitrogen each have a concentration of 5×10¹⁹ cm⁻³ or less, andphotoconductivity of 1000 times or more with respect to darkconductivity is included. Further, boron (B) of 10 to 1000 ppm may beadded to the i-type semiconductor layer.

Then, as shown in FIG. 8C, in order to form a plurality of unit cellsover the same substrate, openings M₁ to M_(n) and C₁ to C_(n) are formedin the photoelectric conversion layer 405 by a laser processing method(laser scribe). The openings C₁ to C_(n) that are openings forelectrically isolation are provided to form unit cells U₁ to U_(n), andthe openings M₁ to M_(n) are openings for forming a connection betweenthe transparent electrode layer and a rear surface electrode layer. Itis to be noted that the openings M₁ to M_(n) and C₁ to C_(n) reach thesubstrate 401 in FIG. 8C; however, the openings M₁ to M_(n) may beformed so that transparent electrode layers T₁ to T_(n), connectionelectrode layers E₁ to E_(n), and rear surface electrode layers D₁ toD_(n+1) are electrically connected to each other in the subsequentprocesses. That is, the openings M₁ to M_(n) may be formed to reach thesubstrate 401 or to reach the transparent electrode layer 402. Inaddition, the openings C₁ to C_(n) may be formed so as to electricallyisolate an element in the subsequent processes. A kind of a laser usedfor a laser processing method is not limited; however, an Nd-YAG laser,an excimer laser, or the like is used. In any case, by performing alaser process in a state where the transparent electrode layer 402 andthe photoelectric conversion layer 405 are stacked, it is possible toprevent the transparent electrode layer from being peeled off from thesubstrate in the laser process.

In such a manner, the transparent electrode layer 402 is divided into T₁to T_(n), and the photoelectric conversion layer 405 is divided into K₁to K_(n).

Next, as shown in FIG. 9A, the openings M₁ to M_(n) are filled with aconductive paste by an ink jet method, a screen printing method, or thelike to form the connection electrode layers E₁ to E_(n).

As a conductive paste, a conductive paste containing a metal materialsuch as silver (Ag), gold (Au), copper (Cu), or nickel (Ni) or aconductive carbon paste can be used. In this embodiment, the connectionelectrode layers E₁ to E_(n) are formed using a silver (Ag) paste.

Subsequently, the openings C₁ to C_(n) are filled with insulating resinlayers Z₁ to Z_(n) to electrically isolate an element. The insulatingresin layers Z₁ to Z_(n) are formed by an ink jet method, a screenprinting method, or the like.

In a case where the insulating resin layers Z₁ to Z_(n) are formed by anink jet method, as a material of the insulating resin layer, acomposition including a photosensitive material may be used. Forexample, a positive resist obtained by dissolving or dispersing anovolac resin and a naphthoquinone-diazide compound that is aphotosensitive material in a solvent; or a negative resist obtained bydissolving or dispersing a base resin, diphenylsilanediol, an acidgenerating agent, and the like in a solvent is used. As the solvent, anorganic solvent like esters such as butyl acetate or ethyl acetate,alcohols such as isopropyl alcohol or ethyl alcohol, methyl ethylketone, or acetone is used. A concentration of the solvent may beappropriately set depending on a kind or the like of a resist.

In a case where the insulating resin layers Z₁ to Z_(n) are formed by ascreen printing method, the insulating resin layers Z₁ to Z_(n) areformed according to the following steps. A phenoxy resin, cyclohexane,isophorone, high resistance carbon black, aerosil, a dispersing agent, adefoaming agent, and a leveling agent are prepared as insulating resinraw materials for forming the insulating resin layers Z₁ to Z_(n).

First, among the above raw materials, the phenoxy resin is completelydissolved in a mixture solvent of cyclohexanone and isophorone, and isdispersed for 48 hours by a ball mill made of zirconia with carbonblack, aerosil, and the dispersing agent. Next, the defoaming agent andthe leveling agent are added and are further mixed for two hours. Then,a thermal crosslinking reactive resin such as an n-butylated melamineresin and a hardening accelerator are added thereto.

These are further mixed and dispersed to obtain an insulating resincomposition for a passivation film.

An insulating film is formed by a screen printing method using theobtained insulating resin composition ink. After coating with theinsulating resin composition ink, thermal hardening is performed in anoven for 20 minutes at 160° C. to obtain the insulating resin layers Z₁to Z_(n).

Although the connection electrode layers E₁ to E_(n) are formed first inthis embodiment, either the connection electrode layers E₁ to E_(n) andthe insulating resin layers Z₁ to Z_(n) may be formed first.

Next, the rear surface electrode layers D₁ to D_(n+1) are formed asshown in FIG. 9B. The rear surface electrode layers D₁ to D_(n+1) may beformed by a sputtering method, an evaporation method, a plating method,a screen printing method, an ink jet method, or the like.

In a case where a sputtering method is used, an element selected fromtantalum (Ta), tungsten (W), titanium (Ti), molybdenum (Mo), or aluminum(Al), or an alloy material or a compound material containing the aboveelements as a main component can be used as a material for the rearsurface electrode layers D₁ to D_(n+1). In a case where an ink jetmethod is used, a conductive paste containing a metal material such assilver (Ag), gold (Au), copper (Cu), or nickel (Ni) can be used as amaterial for the rear surface electrode layers D₁ to D_(n+1).

A method for forming the rear surface electrode layers D₁ to D_(n+1) bya screen printing method is explained below. A graphite powder, a highconductive black, an oleic acid (dispersing agent), and isophorone(solvent) are prepared as an ink to be used.

These materials are put into a ball mill to be crushed to obtain finerparticles. Then, 20 wt % of γ-butyrolactone lacquer of a saturatedpolyester resin is added thereto.

Then, the defoaming agent and the leveling agent are added thereto.

In addition, a paste obtained after dispersing and mixing by the ballmill is further dispersed by a three-roll mill to obtain a conductivecarbon paste.

Ethyl acetoacetate block body (solid content 80 wt %, NCO content 10 wt%) Coronate 2513, which is obtained by blocking an isocyanate group ofhexamethylenediisocyanate-based polyisocyanate of aliphaticpolyfunctional isocyanate by ethyl acetoacetate and by diluting it witha solvent of cellosolve acetate and xylene at a rate of 1 to 1, is addedto this paste. Then, the paste is mixed sufficiently by a disper anddefoamed sufficiently. Thus, a conductive carbon paste is obtained.

Then, the obtained conductive carbon paste is printed into apredetermined pattern by a screen printing method, and after beingleveled and dried, the paste is firmly hardened at 150° C. for 30minutes to form the rear surface electrode layers D₁ to D_(n+1) as shownin FIG. 9B.

The respective rear surface electrode layers D₁ to D_(n+1) are formed soas to be connected to the transparent electrode layers T₁ to T_(n)through the openings M₁ to M_(n). The openings M₁ to M_(n) are filledwith the connection electrode layers E₁ to E_(n). The rear surfaceelectrode layers D₁ to D_(n+1) are electrically connected to thetransparent electrode layers T₁ to T_(n), respectively, through theconnection electrode layers E₁ to E_(n).

Next, a sealing resin layer 406 is formed by a printing method (refer toFIG. 9C). In this embodiment, an epoxy resin, γ-butyrolactone,isophorone, a defoaming agent, and a leveling agent are prepared as araw material of a sealing resin.

First, among the above raw materials, the epoxy resin is completelydissolved in a mixture solvent of γ-butyrolactone/isophorone, and isdispersed by a ball mill made of zirconia. Subsequently, the defoamingagent and the leveling agent are further added thereto. The solvent isfurther mixed, and a butylated melamine resin is added as a thermalcross-linking reactive component.

These are further mixed and dispersed to obtain an composition having atransparent and insulating property for a surface protecting and sealingfilm.

The sealing resin layer 406 is formed by a screen printing method usingthe obtained ink composition having a transparent and insulatingproperty for a surface protecting and sealing film and is thermallyhardened at 150° C. for 30 minutes. In the sealing resin layer 406,openings are formed over the rear surface electrode layers D₁ andD_(n+1) so that the rear surface electrode is connected to an externalcircuit board through the openings.

As described above, unit cells U₁ to U_(n) having the transparentelectrode layers T₁ to T_(n), the photoelectric conversion layers K₁ toK_(n), the connection electrode layers E₁ to E_(n), and the rear surfaceelectrode layers D₁ to D_(n+1) are formed over the substrate 401. Npieces of series-connected solar batteries can be manufactured byconnecting the adjacent rear surface electrode layers D₁ to D_(n+1) tothe transparent electrode layers T₁ to T_(n) through the openings M₁ toM_(n). The rear surface electrode layer D₁ becomes an extractingelectrode of the transparent electrode layer T₁ in the unit cell U₁whereas the rear surface electrode layer D_(n+1) becomes an extractingelectrode of the transparent electrode layer T_(n) in the unit cellU_(n).

Next, an example in which the above solar battery is applied to awristwatch is explained below.

FIG. 10 shows a top view in which a solar battery that is applied to awristwatch is seen from a rear surface electrode side. FIG. 10 shows anexample of a wristwatch in which a solar battery is arranged on thelower side (portion where a movement of a wristwatch is incorporated) ofa semi-light transmitting dial. A substrate 501 is an organic resin filmhaving a thickness of 70 μm. Although any of the organic resin materialsdescribed in the explanation of the substrate 401 can be applied, a PENsubstrate is typically used for the substrate 501. The shape of thesubstrate 501 is not limited to a circle. An insertion port 507 of apointer shaft is provided at the center of the substrate 501.

In the solar battery, a transparent electrode layer, a photoelectricconversion layer, a rear surface electrode layer, and a sealing resinlayer are sequentially stacked over the substrate 501. Although fourunit cells YU₁ to YU₄ are concentrically arranged over the substrate 501in FIG. 10, the structure of series connection of the solar battery isbasically the same as that of FIG. 9C.

In FIG. 10, the unit cells YU₁ to YU₄ are defined by an opening YC₀formed in a transparent electrode layer and a photoelectric conversionlayer, and by openings YC₁ to YC₄ inside the opening YC₀. The openingsYC₀ to YC₄ are filled with insulating resin layers YZ₀ to YZ₄.

Connection electrodes YE₁ to YE₄ are formed by an ink jet method using ametal paste such as a silver (Ag) paste in the photoelectric conversionlayer and the transparent electrode layer. Rear surface electrode layersYD₁ to YD₄ are respectively connected to transparent electrode layersYT₂ to YT₄ of the adjacent unit cells YU₁ to YU₄ through the connectionelectrode layers YE₁ to YE₄ formed in the openings YM₂ to YM₄. A sealingresin layer 504 is formed over the entire surface of the rear surfaceelectrodes except for connection portions 505 and 506 that are connectedto a circuit board of the wristwatch. An output electrode YD₀ of thetransparent electrode is formed at the connection portion 505 that isconnected to the circuit board, and the output electrode YD₀ isconnected to the transparent electrode through an opening YM₁. As shownin FIG. 10, the output electrode YD₀ is formed to be separated from therear surface electrode layer YD₁. The rear surface electrode layer YD₄,which is the other connection portion 506, also serves as an outputelectrode.

FIG. 11A shows a cross-sectional view taken along a line A-A′ of theperiphery of the connection portion 505 that is connected to the circuitboard in FIG. 10. The transparent electrode layer, the photoelectricconversion layer, and the rear surface electrode layer are formed overthe substrate 501. The openings YC₀ and YM₁ are formed by a laserprocessing method in the transparent electrode layer and thephotoelectric conversion layer, and the insulating layer YZ₀ is formedin the opening YC₀ to fill the opening. The output electrode YD₀ on thetransparent electrode side is connected to the transparent electrodelayer YT₁ of the unit cell YU₁ through a connection electrode YE₀ formedin the opening YM₁. The sealing resin layer 504 is formed over the rearsurface electrode layer YD₁ of the unit cell YU₁.

Similarly, FIG. 11B shows a cross-sectional view taken along a line B-B′of the periphery of the connection portion 506 that is connected to anexternal circuit. The transparent electrode layer YT₄, a photoelectricconversion layer YK₄, and the rear surface electrode layer YD₄ areformed over the substrate 501. The transparent electrode layer YT₄ isformed inside the edge by the opening YC₀. The insulating layer YZ₀fills the opening. Although the sealing resin layer is formed over therear surface electrode layer YD₄, it is not formed over the connectionportion 506.

FIG. 11C shows a cross-sectional view taken along a line C-C′ of theperiphery of the connection portion of the adjacent unit cells in FIG.10. The transparent electrode layers YT₃ and YT₄ are formed over thesubstrate 501, and are electrically isolated from each other by theinsulating layer YZ₃ formed in the opening YC₃. Similarly, thephotoelectric conversion layers YK₃ and YK₄ are also isolated. The rearsurface electrode layer YD₃ is connected to the transparent electrodelayer YT₄ through the connection electrode layer YE₄ formed in theopening YM₄, whereby the unit cells YU₃ and YU₄ are connected.

As described above, it is possible to form the solar battery in whichthe four unit cells YU₁ to YU₄ are connected in series. In solarbatteries incorporated in various electric devices such as a calculatoror a watch, there is an adopted method of direct connection using a coilspring or a plate spring, in addition to a connecting method usingsoldering or a thermosetting adhesive agent to connect a solar batteryto a circuit in the electric device. FIG. 12 is a view for explaining anexample of such a connection method where connection between aphotoelectric conversion device 512 and a circuit board 516 is madethrough a connection spring 514. The structure of the photoelectricconversion device 512 is simply shown, and a rear surface electrode 522,an insulating resin 523, and a sealing resin 524 that are formed over asubstrate 521 is shown. In addition, a stainless steel structural body513, a support body 511, and the like are also included. The connectionspring 514 is in contact with the rear surface electrode 522 in anopening portion of the sealing resin 524, and electrical connection tothe circuit board 516 is formed through a terminal portion 515. Aconnection structure of a contact by applying pressure using mechanicalforce like this does not give severe damage to a solar battery comparedwith a connection method such as soldering or heat sealing, and does notcause a yield to be reduced in a manufacturing process.

FIG. 13A shows a wristwatch in which a solar battery formed as describedabove is incorporated. In FIG. 13A, reference numeral 551 denotes achassis; 552, the solar battery shown in FIG. 10 and FIGS. 11A to 11C;553, a dial having a long hand and a short hand; and 554, a cover.

Further, FIG. 13B shows a calculator in which the solar batterymanufactured by the present invention is incorporated. In FIG. 13B,reference numeral 561 denotes a chassis; 562, a solar battery; 563,buttons; and 564, a display panel. As the solar battery 562, a solarbattery in which unit cells are connected in series as shown in FIG. 9Cmay be used.

It is to be noted that this embodiment can be combined with anydescription in Embodiment Modes 1 and 2.

Embodiment 2

In this embodiment, an example of manufacturing a photosensor will beexplained with reference to FIGS. 14A and 14B, FIGS. 15A to 15C, FIGS.16A and 16B, FIGS. 17A and 17B, FIG. 18, FIGS. 19A to 19D, FIGS. 20A to20D, FIG. 24, FIG. 25, and FIG. 26.

First, processes to forming the photoelectric conversion layer 405 shownin FIG. 8B are performed, which is based on Embodiment 1 (refer to FIG.14A). It is to be noted that the same portions as Embodiment 1 aredenoted by the same reference numeral, and the processes, materials, andthe like shown in Embodiment 1 are adopted here in a case where they arenot particularly mentioned.

Next, openings XM₁ to XM_(n), XC_(1a) to XC_(na), and XC_(1b) to XC_(nb)are formed in the photoelectric conversion layer 405 by a laserprocessing method (laser scribe) (refer to FIG. 14B). It is to be notedthat, in FIG. 14B, the openings XM₁ to XM_(n), XC_(1a) to XC_(na), andXC_(1b), to XC_(nb) reach the substrate 401. However, the openings XM₁to XM_(n) may be formed so that transparent electrode layers XT₁ toXT_(n) can be electrically connected to connection electrode layersXE_(1b) to XE_(nb) in the subsequent process. In other words, theopenings XM₁ to XM_(n) may be formed so as to reach the substrate 401 orso as to reach the transparent electrode layer 402. Further, theopenings XC_(1a) to XC_(na) and XC_(1b) to XC_(nb) may be formed so asto electrically isolate an element in the subsequent process.

The openings XC_(1a) to XC_(na) and XC_(1b) to XC_(nb) are openings forelectrically isolation, which are provided to form unit cells XU₁ toXU_(n). The unit cell XU_(i) (i=1, 2, . . . , n) includes the openingsXC_(ia) and XC_(ib). Further, the openings XM₁ to XM_(n) openings forforming connection of a transparent electrode layer and an electrodelayer.

By forming the openings XM₁ to XM_(n), XC_(1a) to XC_(na), and XC_(1b)to XC_(nb), the transparent electrode layer 402 is divided into XT₁ toXT_(n), and the photoelectric conversion layer 405 is divided into XK₁to XK_(n).

Subsequently, the openings XM₁ to XM_(n) are filled with a conductivepaste by an ink jet method, a screen printing method, or the like toform the connection electrode layers XE_(1a), to XE_(na) as shown inFIG. 15A. In addition, connection electrode layers XE_(1a) to XE_(na)are formed over a top layer of the photoelectric conversion layer 405,which is the n-type semiconductor layer 405 n in this embodiment. As amaterial for the connection electrode layers XE_(1a) to XE_(na) andXE_(1b) to XE_(nb), the same material as the connection electrode layersE₁ to E_(n) described in Embodiment 1 may be used.

Next, the openings XC_(1a) to XC_(na) and XC_(1b) to XC_(nb) are filledwith insulating resin layers XZ_(1a) to XZ_(na) and XZ_(1b), to XZ_(nb)to electrically isolate an element (refer to FIG. 15B). The insulatingresin layers XZ_(1a) to XZ_(na) and XZ_(1b) to XZ_(nb) may be formed bythe same process as that of the insulating resin layers Z₁ to Z_(n)described in Embodiment 1.

In this embodiment, the connection electrode layers XE_(1a) to XE_(na)and XE_(1b) to XE_(nb) are formed first. However, either the connectionelectrode layers XE_(1a) to XE_(na) and XE_(1b) to XE_(nb), or theinsulating resin layers XZ_(1a) to XZ_(na) and XZ_(1b) to XZ_(nb) may befirst formed.

Next, an insulating layer 601 is formed. The insulating layer 601 may beformed by the same process, material, and the like as those of thesealing resin layer 406 in Embodiment 1.

Then, openings XH_(1a) to XH_(1n) and XH_(1b) to XH_(nb) are formed inthe insulating layer 601 by a laser processing method (laser scribe)(refer to FIG. 16A). The opening XH_(ia) (i=1, 2, . . . , n) is formedso as to reach the connection electrode layer XE_(ia), and the openingXH_(ib) is formed so as to reach a connection electrode layer XE_(ib).

In addition, the openings to XH_(1a) and XH_(in) to XH_(nb) are filledto form electrode layers XG_(1a) to XG_(na) and XG_(1b) to XG_(nb) withthe same material as the connection electrode layers XE_(1a) to XE_(na)and XE_(1b) to XE_(nb). The electrode layer XG_(ia) (i=1, 2, . . . , n)is connected to the connection electrode layer XE_(ia) through theopening XH_(ia), and the electrode layer XG_(ib) is connected to theconnection electrode layer XE_(ib) through the opening XH_(ib).

Subsequently, the substrate 401, the transparent electrode layers XT₁ toXT_(n), the photoelectric conversion layers XK₁ to XK_(n), theconnection electrode layers XE_(1a) to XE_(na) and XE_(1b) to XE_(nb),the insulating resin layers XZ_(1a) to XZ_(na) and XZ_(1b) to XZ_(nb),the insulating layer 601, and the electrode layers XG_(1a) to XG_(na)and XG_(1b) to XG_(nb) are each divided into unit cells XU₁ to XU_(n) bylaser scribe. For division into the unit cells XU₁ to XU_(n), regionsbetween the insulating resin layers XZ_(1b) and XZ_(2a) to between theinsulating resin layers XZ_((n−1)b) and XZ_(na) may be irradiated with alaser beam 603 (refer to FIGS. 17A and 17B).

FIG. 18 shows a mode in which the unit cell XU_(i) (i=1, 2, . . . , n)of a photosensor manufactured as described above is connected to acircuit board provided with an amplifier circuit.

In FIG. 18, reference numeral 610 denotes a substrate; 612, a baseinsulating film; and 613, a gate insulating film. Since light to bereceived transmits through the substrate 610, the base insulating film612, and the gate insulating film 613, materials thereof having a highlight transmitting property are desired to be used.

An amplifier circuit, for example, transistors 604 and 605 such as thinfilm transistors (TFT), which constitutes a current mirror circuit 607,is formed over the base insulating film 612. A wiring 614, a wiring 615,and an electrode 650 are formed over the gate insulating film 613 of theTFTs 604 and 605.

Interlayer insulating films 616 and 617 are formed over the gateinsulating film 613, the wiring 614, the wiring 615, and the electrode650. A wiring 684 connected to the wiring 614, an electrode 685connected to the wiring 615, and an electrode 681 connected to theelectrode 650 are formed over the interlayer insulating film 617.

In addition, a sealing layer 624 is formed over the interlayerinsulating film 617, the TFTs 604 and 605, the wiring 684, the electrode685, and the electrode 681. Further, an electrode 623 connected to thewiring 684, an electrode 621 connected to the electrode 685, and anelectrode 622 connected to the electrode 681 are formed over the sealinglayer 624.

The circuit board formed as described above and the unit cell XU_(i) areattached to each other. Therefore, the electrode 623 and the electrodelayer XG_(ia), and the electrode 621 and the electrode layer XG_(ib) areelectrically connected to each other through a conductor 664, forexample, a conductive paste.

As the conductive paste, a conductive paste including a metal materialsuch as silver (Ag), gold (Au), copper (Cu), or nickel (Ni), or aconductive carbon paste can be used. In this embodiment, the conductor664 is formed using a silver (Ag) paste.

In FIG. 18, light enters the photoelectric conversion layer XK_(i) froma substrate 610 side and a substrate 401 side of the unit cell XU_(i) asshown by arrows in the view. Thus, a light current is generated, andlight can be detected.

However, light may enter the photoelectric conversion layer from onlythe substrate 610 side or only the substrate 401 side as needed. Whenlight enter the photoelectric conversion layer from one of the substrate610 side and the substrate 401 side, a material that does not transmitlight may used for the substrate of the other side or the substrate ofthe other side may be covered with the material that does not transmitlight.

Next, a process for manufacturing a circuit board will be explainedbelow with reference to FIGS. 19A to 19D, and FIGS. 20A to 20D.

First, an element is formed over the substrate 610. In this embodiment,AN 100 produced by Asahi Glass CO., LTD, which is one of glasssubstrates, is used as the substrate 610.

Subsequently, a silicon oxide film containing nitrogen (with a filmthickness of 100 nm) to be the base insulating film 612 is formed by aplasma CVD method, and a semiconductor film such as an amorphous siliconfilm containing hydrogen (with a film thickness of 54 nm) is stackedwithout being exposed to an atmospheric air. Further, the baseinsulating film 612 may be formed by stacking a silicon oxide film, asilicon nitride film, and a silicon oxide film containing nitrogen. Forexample, a film in which a silicon nitride film containing oxygen with afilm thickness of 50 nm and a silicon oxide film containing nitrogenwith a film thickness of 100 nm are stacked may be formed as the baseinsulating film 612. It is to be noted that the silicon oxide filmcontaining nitrogen and the silicon nitride film serve as a blockinglayer that prevents an impurity such as an alkali metal from diffusingfrom the glass substrate.

Then, the amorphous silicon film is crystallized by a solid-phase growthmethod, a laser crystallization method, a crystallization method using acatalyst metal, or the like to form a semiconductor film having acrystalline structure (a crystalline semiconductor film), for example, apolycrystalline silicon film. Here, a polycrystalline silicon film isobtained by a crystallization method using a catalyst element. Asolution containing nickel of 10 ppm by weight is added to the amorphoussilicon film by a spinner. It is to be noted that a nickel element maybe dispersed over the entire surface by a sputtering method instead ofadding the solution. Then, heat treatment is performed forcrystallization to form a semiconductor film having a crystallinestructure (here, a polycrystalline silicon film). Here, apolycrystalline silicon film is obtained by heat treatment forcrystallization (at 550° C. for 4 hours) after the heat treatment (at500° C. for one hour).

Next, an oxide film over the surface of the polycrystalline silicon filmis removed by a dilute hydrofluoric acid or the like. Thereafter,irradiation of a laser beam for raising a degree of crystallization andrepairing a defect left in a crystal grain is performed.

It is to be noted that the following laser irradiation method may beemployed in a case where a crystalline semiconductor film is obtained bycrystallizing the amorphous silicon film by a laser crystallizationmethod or in a case where laser irradiation is performed to repair adefect left in a crystal grain after obtaining a semiconductor filmhaving a crystalline structure.

A continuous wave laser beam (CW laser beam) or a pulsed wave laser beam(pulsed laser beam) can be used for the laser irradiation. As the laserbeam that can be used here, one or more of a gas laser such as an Arlaser, a Kr laser, or an excimer laser; a laser using, as a medium,single crystalline YAG, YVO₄, forsterite (Mg₂SiO₄), YAlO₃, or GdVO₄ orpolycrystalline (ceramic) YAG, Y₂O₃, YVO₄, YAlO₃, or GdVO₄, doped withone or more of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta as a dopant; a glasslaser; a ruby laser; an alexandrite laser; a Ti:sapphire laser; a coppervapor laser; and a gold vapor laser, can be used. A crystal with a largegrain size can be obtained by irradiation of a laser beam having afundamental wave of such lasers or second, third, and fourth harmonic ofthe fundamental wave. For example, the second harmonic (532 nm) or thethird harmonic (355 nm) of an Nd:YVO₄ laser (fundamental wave of 1064nm) can be used. In this case, energy density of approximately 0.01 to100 MW/cm² (preferably, 0.1 to 10 MW/cm²) is required for a laser. Thescanning speed is set to be approximately 10 to 2000 cm/sec for theirradiation.

It is to be noted that a laser using, as a medium, single crystallineYAG, YVO₄, forsterite (Mg₂SiO₄), YAlO₃, or GdVO₄ or polycrystalline(ceramic) YAG, Y₂O₃, YVO₄, YAlO₃, or GdVO₄, to which one or more of Nd,Yb, Cr, Ti, Ho, Er, Tm, and Ta as a dopant is added; an Ar ion laser; aKr ion laser; or a Ti:sapphire laser can be continuously oscillated.Further, pulse oscillation thereof can be performed with an oscillationfrequency of 10 MHz or more by carrying out Q switch operation or modesynchronization. When a laser beam is oscillated with an oscillationfrequency of 10 MHz or more, a semiconductor film is irradiated with anext pulse while the semiconductor film is melted by the laser beam andsolidified. Therefore, differing from a case of using a pulsed laserwith a low oscillation frequency, a solid-liquid interface can becontinuously moved in the semiconductor film, so that crystal grainsthat continuously grow toward a scanning direction can be obtained.

When ceramic (polycrystalline) is used as a medium, the medium can beformed to have a free shape in a short time at low cost. When a singlecrystal is used, a columnar medium with several mm in diameter andseveral tens of mm in length is usually used. In a case of using theceramic, a medium larger than the case of using the single crystal canbe formed.

A concentration of a dopant such as Nd or Yb in a medium, which directlycontributes to light emission, cannot be changed largely in both casesof the single crystal and the poly crystal; therefore, there is alimitation to some extent in improvement in output of a laser byincreasing the concentration. However, in the case of the ceramic, thesize of a medium can be significantly increased as compared to the caseof the single crystal; therefore, drastic improvement in output of alaser can be expected.

Further, in the case of the ceramic, a medium with a parallelepipedshape or a cuboid shape can be easily formed. In a case of using amedium having such a shape, when oscillated light is made to travel in azigzag inside the medium, a long path of the oscillated light can beobtained. Therefore, amplitude is increased and a laser beam can beoscillated at high output. Furthermore, a cross-sectional shape of alaser beam, which is emitted from a medium having such a shape, is aquadrangular shape; therefore, as compared to a laser beam with acircular shape, the laser beam with the quadrangular shape in crosssection has an advantage to be shaped into a linear beam. By shaping alaser beam emitted in such a manner using an optical system, a linearbeam with 1 mm or less in length of a short side and several mm toseveral m in length of a long side can be easily obtained. In addition,when a medium is uniformly irradiated with excited light, a linear beamis emitted with a uniform energy distribution in a long side direction.

When a semiconductor film is irradiated with such a linear beam, anentire surface of the semiconductor film can be uniformly annealed. In acase where uniform annealing is required from one edge to the other edgeof the linear beam, an ingenuity in which slits are arranged on the bothedges of the linear beam so as to shield a portion with attenuatedenergy from light, or the like is required.

In a case where laser irradiation is performed in an atmospheric air oran oxide atmosphere, an oxide film is formed over a surface of thesemiconductor film by the laser irradiation.

Then, in addition to the oxide film formed by the laser beamirradiation, a barrier layer made of an oxide film having a thickness of1 to 5 nm in total is formed by treating a surface with ozone water for120 seconds. The barrier layer is formed in order to remove a catalystelement, which is added for crystallization, such as nickel (Ni) fromthe film. Although the barrier layer is formed by using ozone waterhere, a barrier layer may also be formed by a method of oxidizing asurface of a semiconductor film having a crystalline structure by UV-rayirradiation in an oxygen atmosphere; a method of oxidizing a surface ofa semiconductor film having a crystalline structure by oxygen plasmatreatment; by a method of depositing an oxide film having a thickness ofapproximately 1 to 10 nm using a plasma CVD method, a sputtering method,an evaporation method, or the like. In addition, before forming thebarrier layer, the oxide film formed by laser beam irradiation may beremoved.

Subsequently, over the barrier layer, an amorphous silicon filmcontaining an argon element is formed to have a thickness of 10 nm to400 nm, for example 100 nm here, by a sputtering method to serve as agettering site. Here, the amorphous silicon film containing an argonelement is formed in an atmospheric air containing argon using a silicontarget. When a plasma CVD method is used to form the amorphous siliconfilm containing an argon element, the film formation condition is asfollows: a flow ratio of monosilane to argon (SiH₄: Ar) is set to be1:99; film formation pressure is set to be 6.665 Pa; RF power density isset to be 0.087 W/cm²; and a film formation temperature is set to be350° C.

Thereafter, a furnace heated to 650° C. is used for heat treatment forthree minutes to remove a catalyst element (gettering). By thistreatment, a catalyst element concentration in the semiconductor filmhaving a crystalline structure is reduced. A lamp annealing apparatusmay also be used instead of the furnace.

Subsequently, the amorphous silicon film containing an argon element,which is a gettering site, is selectively removed with the barrier layeras an etching stopper, and then, the barrier layer is selectivelyremoved by dilute hydrofluoric acid. It is to be noted that there is atendency that nickel easily moves to a region with a high oxygenconcentration in gettering, and thus, it is desirable that the barrierlayer made of the oxide film be removed after gettering.

It is to be noted that, in a case where crystallization of asemiconductor film using a catalytic element is not performed, the abovedescribed processes such as the formation of the barrier layer, theformation of the gettering site, the heat treatment for gettering, theremoval of the gettering site, and the removal of the barrier layer arenot required.

Next, after a thin oxide film is formed with ozone water over thesurface of the obtained semiconductor film having a crystallinestructure (such as a crystalline silicon film), a mask made of resist isformed by using a first photomask, and etching treatment is performed toobtain a desired shape, thereby forming semiconductor films 631 and 632separated in island shapes (referred to as “island-shape semiconductorregions” in the present specification) (refer to FIG. 19A). Afterforming the island-shape semiconductor regions, the mask made of resistis removed.

Subsequently, if necessary, doping of the minute amount of an impurityelement (boron or phosphorus) is performed to control a threshold valueof a TFT. Here, an ion doping method is used, in which diborane (B₂H₆)is not separated by mass but excited by plasma.

Next, the oxide film is removed by using an etchant containinghydrofluoric acid at the same time as surfaces of the island-shapesemiconductor regions 631 and 632 are washed. Thereafter, an insulatingfilm containing silicon as its main component, which serves as a gateinsulating film 613, is formed. Here, a silicon oxide film containingnitrogen (composition ratio: Si=32%, O-59%, N=7%, H=2%) is formed tohave a thickness of 115 nm by a plasma CVD method.

Then, after a metal film is formed over the gate insulating film 613, asecond photomask is used to form gate electrodes 634 and 635, wirings614 and 615, and an electrode 650 (refer to FIG. 19B). For example, asthe metal film, a film in which tantalum nitride (TaN) and tungsten (W)are stacked to be 30 nm and 370 nm, respectively, is used.

In addition to the above materials, as the gate electrodes 634 and 635,the wirings 614 and 615, and the electrode 650, a single-layer film madeof an element selected from titanium (Ti), tungsten (W), tantalum (Ta),molybdenum (Mo), neodymium (Nd), cobalt (Co), zirconium (Zr), zinc (Zn),ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir),platinum (Pt), aluminum (Al), gold (Au), silver (Ag), or copper (Cu), oran alloy material or a compound material containing the above element asits main component; or a single-layer film made of nitride thereof suchas titanium nitride, tungsten nitride, tantalum nitride, or molybdenumnitride can be used.

The wiring 614 extends to an upper side of a channel formation region inthe TFT 605 of the amplifier circuit to also serve as the gate electrode634.

The wiring 615 is connected to a drain electrode (also referred to as adrain wiring) or a source electrode (also referred to as a sourcewiring) in the TFT 604.

Then, an impurity imparting one conductivity type is introduced to theisland-shape semiconductor regions 631 and 632 to form a source regionor a drain region 637 of the TFT 605, and a source region or a drainregion 638 of the TFT 604. An n-channel TFT is formed in thisembodiment; therefore, an n-type impurity, for example phosphorus (P) orarsenic (As), is introduced to the island-shape semiconductor regions631 and 632 (refer to FIG. 19C).

Subsequently, after a first interlayer insulating film including asilicon oxide film (not shown) is formed to have a thickness of 50 nm bya CVD method, a process for activation treatment of an impurity elementadded to each island-shape semiconductor region is performed. Theactivation process is performed by a rapid thermal annealing method (RTAmethod) using a lamp light source, a method of irradiation of a YAGlaser or an excimer laser from a rear surface, heat treatment using afurnace, or a method that is a combination of any of the foregoingmethods.

Next, a second interlayer insulating film 616 including a siliconnitride film that contains hydrogen and oxygen is formed to have a filmthickness of, for example, 10 nm.

Subsequently, a third interlayer insulating film 617 made of aninsulating material is formed over the second interlayer insulating film616 (refer to FIG. 19D). As for the third interlayer insulating film617, an insulating film obtained by a CVD method can be used. In orderto improve adhesiveness, a silicon oxide film containing nitrogen with afilm thickness of 900 nm is formed as the third interlayer insulatingfilm 617 in this embodiment.

Then, heat treatment (at 300 to 550° C. for 1 to 12 hours, for example,at 410° C. in an nitrogen atmosphere for one hour) is performed tohydrogenate the island-shape semiconductor films. This process isperformed so as to terminate a dangling bond of the island-shapesemiconductor films by hydrogen contained in the second interlayerinsulating film 616. The island-shape semiconductor films can behydrogenated regardless of whether or not the gate insulating film 613is formed.

Further, as the third interlayer insulating film 617, an insulating filmusing siloxane or a stacked structure thereof can be used.

Siloxane is formed of a skeleton structure of a bond of silicon (Si) andoxygen (O). As a substituent, an organic group containing at leasthydrogen (such as an alkyl group or an aromatic hydrocarbon) is used. Afluoro group may also be used as the substituent. Moreover, an organicgroup containing at least hydrogen and a fluoro group may be used as thesubstituent.

In a case where an insulating film using siloxane and a stackedstructure thereof are used as the third interlayer insulating film 617,heat treatment for hydrogenating the island-shape semiconductor films isperformed after forming the second interlayer insulating film 616, andthen, the third interlayer insulating film 617 can be formed.

There is an advantage that, by using materials having a highly lighttransmitting property for all materials of the interlayer insulatingfilms 616 and 617, light can be transmitted through the interlayerinsulating films 616 and 617 even when the light enters from thesubstrate 610. It is to be noted that a silicon oxide film formed by aCVD method may be used for the interlayer insulating film 617 other thanthe insulating film using siloxane. When the interlayer insulating film617 is made of a silicon oxide film formed by a CVD method, fixingintensity is improved.

Next, a mask made of resist is formed using a third photomask, and thefirst interlayer insulating film, the second interlayer insulating film616, and the third interlayer insulating film 617 or the gate insulatingfilm 613 are selectively etched to form a contact hole. Then, the maskmade of resist is removed.

It is to be noted that the third interlayer insulating film 617 may beformed as needed. When the third interlayer insulating film 617 is notformed, after forming the second interlayer insulating film 616, thefirst interlayer insulating film, the second interlayer insulating film616, and the gate insulating film 613 are selectively etched to form acontact hole.

Subsequently, after forming a metal stacked film by a sputtering method,a mask made of resist is formed using a fourth photomask, and then, themetal film is selectively etched to form a wiring 684, an electrode 685,an electrode 681, a source or drain electrode 682 of the 604, and asource or drain electrode 683 of the TFT 605 (refer to FIG. 20A). Thewiring 684, the electrode 685, the electrode 681, the source or drainelectrode 682, and the source or drain electrode 683 are formed of asingle-layer conductive film. As such a conductive film, a titanium film(Ti film) is preferable. Instead of the titanium film, a single-layerfilm made of an element selected from tungsten (W), tantalum (Ta),molybdenum (Mo), neodymium (Nd), cobalt (Co), zirconium (Zr), zinc (Zn),ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir),and platinum (Pt), or an alloy material or a compound materialcontaining the above element as its main component; or a single-layerfilm made of nitride thereof such as titanium nitride, tungsten nitride,tantalum nitride, or molybdenum nitride can be used.

Further, in a case where the wiring 684, the electrode 685, theelectrode 681, the source or drain electrode 682, and the source ordrain electrode 683 are formed to have a stacked structure of arefractory metal film and a low resistance metal film (such as analuminum alloy or pure aluminum), the following is performed.

After formation of the state of FIG. 19D, a metal stacked film is formedby a sputtering method, and a mask made of resist is formed using afourth photomask. Then, the first metal film is selectively etched toform a wiring 619, an electrode 620, an electrode 651, a source or drainelectrode 641 of the TFT 604, and a source or drain electrode 642 of theTFT 605 (refer to FIG. 20B). Thereafter, the mask made of resist isremoved. It is to be noted that the metal film in FIG. 20B is formed bystacking three layers of a Ti film with a film thickness of 100 nm, anAl film containing minute amounts of Si with a film thickness of 350 nm,and a Ti film with a film thickness of 100 nm.

Subsequently, a second metal film (such as titanium (Ti) or molybdenum(Mo)) is formed over the wiring 619, the electrode 620, the electrode651, the source or drain electrode 641, and the source or drainelectrode 642. Thereafter, a mask made of resist is formed using a fifthphotomask, and the conductive metal film is selectively etched to form aprotective electrode 618 covering the wiring 619 (refer to FIG. 20B).Here, a Ti film having a film thickness of 200 nm that is obtained by asputtering method is used. Similarly to the wiring 619, each of theelectrode 620, the electrode 651, the source or drain electrode 641 ofthe TFT 604, and the source or drain electrode 642 of the TFT 605 iscovered with the conductive metal film to respectively form protectiveelectrodes 645, 648, 646, and 647. Therefore, the conductive metal filmcovers each side surface where an Al film in a second layer of theelectrode is exposed, and diffusion of an aluminum atom to thesemiconductor film can be prevented.

Next, a sealing layer 624 made of an insulating material (for example,an inorganic insulating film containing silicon) with a thickness of 1to 30 μm is formed over an entire surface to obtain a state of FIG. 20C.Here, as an insulating material film, a silicon oxide film containingnitrogen with a film thickness of 1 μM is formed by a CVD method. Byusing an insulating film by a CVD method, improvement of adhesiveness isattempted.

Subsequently, the sealing layer 624 is etched to form an opening.Thereafter, electrodes 621, 622, and 623 are formed by a sputteringmethod (refer to FIG. 20D). Each of the electrodes 621 to 623 is astacked-layer film of a titanium film (Ti film) (100 nm), a nickel film(Ni film) (300 nm), and a gold film (Au film) (50 nm). Fixing intensityof the electrodes 621 to 623 obtained as described above is more than5N, which is sufficient fixing intensity for a terminal electrode.

As described above, a circuit board is manufactured. Then, asemiconductor device in which a unit cell XU_(i) of a photosensor and acircuit board of this embodiment are incorporated will be explained withreference to FIG. 24, FIG. 25, and FIG. 26.

As shown in FIG. 24, a semiconductor device of this embodiment includesa power supply (bias power supply) 671, a unit cell XU_(i) of aphotosensor, an amplifier circuit (for example, a current mirrorcircuit) 607 constituted by transistors 604 and 605, an output terminal677, and a connection resistance R_(L). In this embodiment, TFTs areused as the transistors 604 and 605, which are formed of n-channel TFTs.A light current is extracted outside by the output terminal 677.

In FIG. 24, a gate electrode of the TFT 604 constituting the currentmirror circuit 607 is electrically connected to a gate electrode of theTFT 605 that also constitutes the current mirror circuit 607 and one ofterminals of the unit cell XU^(i) of a photosensor. One of a sourceregion and a drain region of the TFT 604 is electrically connected tothe other terminal of the unit cell XU_(i) of a photosensor and the gateelectrode of the TFT 605. Further, the other of the source region andthe drain region of the TFT 604 is electrically connected to one of asource region and a drain region of the TRFT 605, the output terminal677, and the connection resistance R_(L).

The gate electrode of the TFT 605 is electrically connected to the gateelectrode of the TFT 604, and one of the source region or the drainregion of the TFT 604. One of the source region and the drain region ofthe TFT 605 is electrically connected to the other of the source regionand the drain region of the TFT 604, the output terminal 677, and theconnection resistance R_(L). Further, the other of the source region andthe drain region of the TFT 605 is electrically connected to one ofterminals of the unit cell XU_(i) of a photosensor. The gate electrodesof the TFTs 604 and 605 are connected to each other; therefore, commonpotential is applied.

One of terminals of the unit cell XU_(i) of a photosensor iselectrically connected to one of the source region and the drain regionof the TFT 604, the gate electrode of the TFT 604, and the gateelectrode of the TFT 605. The other terminal of the unit cell XU_(i) ofa photosensor is connected to the power supply 671.

Further, one of terminals of the connection resistance R_(L) and thepower supply 671 is each connected to ground.

Although two TFTs are shown in FIG. 24, in order to obtain an outputvalue to be increased by m times, one piece of n-channel TFT 604 and inpieces of n-channel TFTs 605 may be arranged (refer to FIG. 25). Forexample, if an output value is desired to be increased by 100 times, onepiece of n-channel TFT 604 and 100 pieces of n-channel TFTs 605 may bearranged. It is to be noted that, in FIG. 25, the same portions as FIG.24 are denoted by the same reference numeral. In FIG. 24, the n-channelTFT 605 is constituted by m pieces of n-channel TFTs 605 that is,n-channel TFTs 605 a, 605 b, 605 c, 605 d, . . . , and 605 m. Thus, alight current generated in the unit cell XU_(i) of a photosensor isamplified to be m times, and be outputted.

Further, although FIG. 24 shows an equivalent circuit diagram in whichthe current mirror circuit 607 is used in an n-channel TFT, only ap-channel may be used instead of the n-channel TFT.

In a case where an amplifier circuit is formed by a p-channel TFT, anequivalent circuit as shown in FIG. 26 is formed. In FIG. 26, the sameportions as FIG. 24 and FIG. 25 are denoted by the same referencenumerals. A unit cell XU_(i) of a photosensor is preferably connected toa current mirror circuit 693 constituted by p-channel TFTs 691 and 692as shown in FIG. 26.

In FIG. 18, FIGS. 19A to 19D, FIGS. 20A to 20D, FIG. 24, FIG. 25, andFIG. 26, each of the n-channel TFTs 604 and 605 and the p-channel TFTs691 and 692 shows an example of a top gate TFT that has a structureincluding one channel formation region (referred to as a “single gatestructure” in the present specification). However, each TFT may have astructure that has a plurality of channel formation regions so as toreduce variation of an on-current value. In addition, in order to reducean off-current value, each of the n-channel TFTs 604 and 605 and thep-channel TFTs 691 and 692 may be provided with a lightly doped drain(LDD) region. The LDD region is a region where an impurity element isadded at a low concentration between a channel formation region and asource region or a drain region which is formed by adding an impurityelement at a high concentration. When the LDD region is provided, thereis an effect that an electric field in the vicinity of the drain regionis reduced and deterioration due to hot carrier injection is prevented.Further, in order to prevent deterioration of an on-current value due tohot carriers, each of the n-channel TFTs 604 and 605 and the p-channelTFTs 691 and 692 may have a structure in which the LDD region isoverlapped with the gate electrode through the gate insulating film(referred to as a “GOLD (Gate-drain Overlapped LDD) structure” in thepresent specification). Alternatively, either of the n-channel TFT orthe p-channel TFT may be provided with the LDD region.

In a case where the GOLD structure is employed, there is an effect thatan electric field in the vicinity of the drain region is furtherrelieved and deterioration due to hot carrier injection is furtherprevented as compared to a case where the LDD region is not overlappedwith the gate electrode. By employing such a GOLD structure, electricfield intensity in the vicinity of the drain region is reduced toprevent the hot carrier injection, which is effective for prevention ofa deterioration phenomenon.

Further, each of the TFTs 604 and 604 constituting the current mirrorcircuit 607 and the TFTs 691 and 692 constituting the current mirrorcircuit 693 may be a bottom gate TFT, for example, a reverse stagger TFTinstead of the top gate TFT. In this case, the gate electrode preferablyhas a light transmitting property so as not to block light to bereceived.

Embodiment 3

In this embodiment, a unit cell of a photosensor having a differentstructure from that of Embodiment 2, and a method for manufacturing theunit cell will be explained with reference to FIGS. 21A to 21C, FIGS.22A to 22C, and FIG. 23. It is to be noted that, in this embodiment, thesame portions as Embodiment 1 and Embodiment 2 are denoted by the samereference numerals, and in a case where materials, processes, and thelike are not particularly described, those of Embodiment 1 andEmbodiment 2 are adopted.

First, processes to forming the photoelectric conversion layer 405 shownin FIG. 813 are performed, which is based on Embodiment 1. Then, aninsulating layer 701 is formed over the photoelectric conversion layer405 (refer to FIG. 21A). The insulating layer 701 may be formed by thesame process, material, and the like as the sealing resin layer 406 inEmbodiment 1.

Subsequently, openings LM₁ to LM_(n), LC_(1a) to LC_(na), and LC_(1b) toLC_(nb) are formed by a laser processing method (laser scribe) from aninsulating layer 701 side (refer to FIG. 21B). Although the openings LM₁to LM_(n), LC_(1a) to LC_(na), and LC_(1b) to LC_(nb) reach thesubstrate 401 in FIG. 21B, the openings LM₁ to LM_(n) may be formed sothat transparent electrode layers LT₁ to LT_(n) and connection electrodelayers LE_(1b) to LE_(nb) are electrically connected to each other inthe subsequent process. In other words, the openings LM₁ to LM_(n) mayreach the substrate 401 or reach the transparent electrode layer 402.Further, the openings LC_(1a) to LC_(na) and LC_(1b) to LC_(nb) may beformed so as to electrically isolate an element in the subsequentprocess.

The openings LC_(1a) to LC_(na) and LC_(1b) to LC_(nb) are openings forelectrically isolation and provided to form unit cells LU₁ to LU_(n).The unit cells LU_(i) (i=1, 2, . . . , n) has the openings LC_(ia) andLC_(ib). Further, the openings LM₁ to LM_(n) are openings for formingconnection of a transparent electrode layer and an electrode layer toeach other.

By forming the openings LM₁ to LM_(n), LC_(1a) to LC_(na), and LC_(1b)to LC_(nb), the transparent electrode layer 402 is divided into LT₁ toLT_(n), and the photoelectric conversion layer 405 is divided into LK₁to LK_(n).

Then, the openings LM₁ to LM_(n) are filled with a conductive paste byan ink jet method, a screen printing method, or the like as shown inFIG. 21C to form electrode layers LE_(1b), to LE_(nb). In addition,electrode layers LE_(1a) to LE_(na) are formed over a top layer of thephotoelectric conversion layer 405, which is the n-type semiconductorlayer 405 n in this embodiment. As a material of the electrode layersLE_(1a) to LE_(na) and LE_(1b) to LE_(nb), the same material as theconnection electrode layers E₁ to E_(n) described in Embodiment 1 may beused.

Next, the openings LC_(1a) to LC_(na) and LC_(1b) to LC_(nb) are filledwith insulating resin layers LZ_(1a) to LZ_(na) and LZ_(nb) to LZ_(nb)to electrically isolate an element (refer to FIG. 22A). The insulatingresin layers LZ_(1a) to LZ_(na) and LZ_(1b) to LZ_(nb) may be formed bythe same process as that of the insulating resin layers Z₁ to Z_(n)described in Embodiment 1.

In this embodiment, the electrode layers LE_(1a) to LE_(na) and LE_(1b)to LE_(nb) are formed first. However, either the electrode layersLE_(1a) to LE_(na) and LZ_(1b) to L_(nb) or the insulating resin layersLZ_(1a) to LZ_(na) and LZ_(1b) to LZ_(nb) may be formed first.

Subsequently, the substrate 401, the transparent electrode layers LT₁ toLT_(n), the photoelectric conversion layers LK₁ to LK_(n), the electrodelayers LE_(1a) to LE_(na) and LE_(1b) to LE_(nb), the insulating resinlayers LZ_(1a) to LZ_(na) and LZ_(1b) to LZ_(nb), and the insulatinglayer 701 are each divided into unit cells LU₁ to LU_(n) by laserdescribe. For division into the unit cells LU₁ to LU_(n), regionsbetween the insulating layers LZ_(1b) and LZ_(2a) to between theinsulating resin layers LZ_((−1)b) and LZ_(na) may be irradiated with alaser beam 703 (refer to FIGS. 22B and 22C).

FIG. 23 shows a mode in which the unit cell LU_(i) (i=1, 2, . . . , n)of a photosensor manufactured as described above is connected to acircuit board provided with an amplifier circuit, which is based onEmbodiment 2. In FIG. 23, the same portions as FIG. 18 are denoted bythe same reference numerals. Further, the circuit board may bemanufactured similarly to Embodiment 2.

It is to be noted that this embodiment can be combined with anydescription of Embodiment Modes 1 and 2 and Embodiments 1 and 2.

Embodiment 4

In this embodiment, an example in which a photosensor that is obtainedby Embodiments 2 and 3 is incorporated into various electronicappliances will be explained. As electronic appliances to which thepresent invention is applied, a computer, a display, a cellular phone, atelevision, and the like can be given. Specific examples of thoseelectronic appliances are shown in FIG. 27, FIGS. 28A and 28B, FIGS. 29Aand 29B, FIG. 30, and FIGS. 31A and 31B.

FIG. 27 shows a cellular phone, which includes a main body (A) 801, amain body (B) 802, a chassis 803, operation keys 804, an audio inputportion 805, an audio output portion 806, a circuit board 807, a displaypanel (A) 808, a display panel (B) 809, a hinge 810, alight-transmitting material portion 811, and a photosensor 812. Thephotosensor 812 may be manufactured based on Embodiments 2 and 3.

The photosensor 812 detects light that passes through thelight-transmitting material portion 811 and controls a luminance of thedisplay panel (A) 808 and the display panel (B) 809 based on illuminanceof the detected external light, or controls illumination of theoperation keys 804 based on the illuminance obtained by the photosensor812. In this manner, a consumption current of the cellular phone can besuppressed.

FIGS. 28A and 28B show other examples of a cellular phone. In FIGS. 28Aand 28B, reference numeral 821 denotes a main body; 822, a chassis; 823,a display panel; 824, operation keys; 825, an audio output portion; 826,an audio input portion; and 827, a photosensor.

In the cellular phone shown in FIG. 28A, a luminance of the displaypanel 823 and the operation keys 824 can be controlled by detectingexternal light by the photosensor 827 provided in the main body 821.

Further, in the cellular phone shown in FIG. 28B, a photosensor 828 isprovided in the main body 821 in addition to the structure of FIG. 28A.By the photosensor 828, a luminance of a backlight provided in a displaypanel 823 can be detected.

FIG. 29A shows a computer, which includes a main body 831, a chassis832, a display portion 833, a key board 834, an external connecting port835, a pointing mouse 836, and the like.

FIG. 29B shows a display device such as a television receiver. Thisdisplay device includes a chassis 841, a supporting body 842, a displayportion 843, and the like.

FIG. 30 shows a detailed structure of a case where a liquid crystalpanel is used for the display portion 833 of the computer shown in FIG.29A and the display portion 843 of the display device shown in FIG. 29B.

A liquid crystal panel 862 shown in FIG. 30 is incorporated in a chassis861, which includes substrates 851 a and 851 b, a liquid crystal layer852 interposed between the substrates 851 a and 851 b, polarizingfilters 855 a and 855 b, a backlight 853, and the like. In the chassis861, a photoelectric conversion element formation region 854 having aphotosensor is formed.

The photoelectric conversion element formation region 854 manufacturedby using the present invention detects amount of light from thebacklight 853, and information thereof is fed back to adjust a luminanceof the liquid crystal panel 862.

FIGS. 31A and 31B show an example in which a photosensor of the presentinvention is incorporated in a camera, for example, a digital camera.FIG. 31A is a perspective view seen from a front side of the digitalcamera. FIG. 31B is a perspective view seen from a back side of thedigital camera. In FIG. 30A, the digital camera is provided with arelease button 871, a main switch 872, a viewfinder 873, a flash portion874, a lens 875, a barrel 876, and a chassis 877.

In FIG. 31B, an eyepiece finder 881, a monitor 882, and operationbuttons 883 are provided.

When the release button 871 is pushed down to the half point, a focusadjustment mechanism and an exposure adjustment mechanism are operated,and when the release button is pushed down to the lowest point, ashutter is opened.

By pushing down or rotating the main switch 872, a power supply of thedigital camera is switched on or off.

The viewfinder 873 is arranged above the lens 875, which is on the frontside of the digital camera, for checking a shooting range and the focuspoint from the eyepiece finder 881 shown in FIG. 31B.

The flash portion 874 is arranged in the upper position on the frontside of the digital camera. When the subject brightness is not enough,auxiliary light is emitted from the flash portion 874, at the same timeas the release button 871 is pushed down and a shutter is opened.

The lens 875 is arranged at the front side of the digital camera andmade of a focusing lens, a zoom lens, and the like. The lens forms aphotographic optical system with a shutter and a diaphragm, which arenot shown. In addition, behind the lens, an imaging device such as a CCD(Charge Coupled Device) is provided.

The barrel 876 moves a lens position to adjust the focus of the focusinglens, the zoom lens, and the like. In shooting, the barrel is slid outto move the lens 875 forward. Further, when carrying the digital camera,the lens 875 is moved backward to be compact. It is to be noted that astructure is employed in this embodiment, in which the subject can bephotographed by zoom by sliding out the barrel; however, the presentinvention is not limited to this structure, and a structure may also beemployed for the digital camera, in which shooting can be performed byzoom without sliding out the barrel with the use of a structure of aphotographic optical system inside the chassis 877.

The eyepiece finder 881 is arranged in the upper position on the backside of the digital camera for looking therethrough in checking ashooting range and the focus point.

The operation buttons 883 are each a button for various functionsprovided on the back side of the digital camera, which includes a set upbutton, a menu button, a display button, a functional button, aselecting button, and the like.

When a photosensor of the present invention is incorporated into thecamera shown in FIGS. 31A and 31B, the photosensor can detect whetherlight exists or not, and light intensity. Thus, exposure adjustment orthe like of a camera can be performed.

A photosensor of the present invention can be applied to otherelectronic appliances, for example, a projection TV, a navigationsystem, and the like. In other words, the photosensor can be used forany electronic appliance as long as it needs to detect light.

It is to be noted that this embodiment can be combined with anydescription in Embodiment Modes 1 and 2 and Embodiments 1 to 3.

In accordance with the present invention, a film formation apparatus canbe achieved, in which damage to a light receiving region and curling ofa substrate in film formation can be suppressed. Further, by forming afilm by using a film formation apparatus of the present invention,damage to a light receiving region and curling of a substrate can besuppressed. Therefore, a highly reliable photoelectric conversion devicecan be obtained.

A film formation apparatus according to the present invention can beapplied to a use of forming a thin film over a lengthy film substrate inaddition to a photoelectric conversion device disclosed in the presentspecification. For example, when a diamond like carbon (DLC) film isformed over a flexible substrate, the present invention can be applied.In addition, a structure of a film formation chamber is made to besuitable for forming a thin film by sputtering, whereby the presentinvention can be applied in forming a transparent conductive film over aflexible substrate.

This application is based on Japanese Patent Application serial no.2005-279117 filed in Japan Patent Office on Sep. 27, 2005, the entirecontents of which are hereby incorporated by reference.

1. A film formation apparatus comprising: a first chamber; a secondchamber; a third chamber provided between the first chamber and thesecond chamber; a slit in the third chamber; and a fourth chamberincluding a roller, wherein the slit is provided with a touch roller atone edge of the slit, the touch roller being a single roller and incontact with a film formation surface of a substrate.
 2. The filmformation apparatus according to claim 1, wherein the first chamberincludes a roller; and wherein the second chamber includes a firstdischarging electrode and a second discharging electrode.
 3. The filmformation apparatus according to claim 1, wherein the first chamberincludes a first discharging electrode and a second dischargingelectrode; and wherein the second chamber includes a third dischargingelectrode and a fourth discharging electrode.
 4. The film formationapparatus according to claim 1, wherein the first chamber includes aroller; and wherein the second chamber includes at least two firstdischarging electrodes and a second discharging electrode.
 5. The filmformation apparatus according to claim 4, wherein the second chamberincludes an insulator between the first discharging electrodes.
 6. Thefilm formation apparatus according to claim 4, wherein the firstdischarging electrodes are formed over the second discharging electrode.7. The film formation apparatus according to claim 1, wherein the firstchamber includes at least two first discharging electrodes and a seconddischarging electrode; and wherein the second chamber includes at leasttwo third discharging electrodes and a fourth discharging electrode. 8.The film formation apparatus according to claim 7, wherein the firstdischarging electrodes are formed over the second discharging electrode,and wherein the third discharging electrodes are formed over the fourthdischarging electrode.
 9. The film formation apparatus according toclaim 7, wherein the first chamber includes an insulator between thefirst discharging electrodes.
 10. The film formation apparatus accordingto claim 7, wherein the second chamber includes an insulator between thethird discharging electrodes.
 11. A film formation apparatus comprising:a first chamber; a second chamber; a third chamber provided between thefirst chamber and the second chamber; and a slit in the third chamber;wherein the third chamber is configured to pass through a substrate fromthe first chamber to the second chamber, wherein the slit is providedwith a touch roller at one edge of the slit, the touch roller being asingle roller and in contact with a film forming surface of thesubstrate.
 12. The film formation apparatus according to claim 11,further comprising a fourth chamber including a roller, wherein theroller is configured to rewind the substrate.
 13. The film formationapparatus according to claim 11, wherein the first chamber includes aroller; and wherein the second chamber includes a first dischargingelectrode and a second discharging electrode.
 14. The film formationapparatus according to claim 11, wherein the first chamber includes afirst discharging electrode and a second discharging electrode; andwherein the second chamber includes a third discharging electrode and afourth discharging electrode.
 15. The film formation apparatus accordingto claim 11, wherein the first chamber includes a roller; and whereinthe second chamber includes at least two first discharging electrodesand a second discharging electrode.
 16. The film formation apparatusaccording to claim 11, wherein the first chamber includes at least twofirst discharging electrodes and a second discharging electrode; andwherein the second chamber includes at least two third dischargingelectrodes and a fourth discharging electrode.
 17. A film formationapparatus comprising: a substrate; a first chamber; a second chamber; athird chamber provided between the first chamber and the second chamber;a slit in the third chamber; and a fourth chamber including a firstroller and a second roller, wherein the third chamber is configured topass through a substrate from the first chamber to the second chamber,wherein the slit is provided with a touch roller at one edge of theslit, the touch roller being a single roller and in contact with a filmformation surface of the substrate, and wherein the second roller isconfigured to supply a protective sheet so as to adhere to the filmformation surface of the substrate.
 18. The film formation apparatusaccording to claim 17, wherein the first chamber includes a roller; andwherein the second chamber includes a first discharging electrode and asecond discharging electrode.
 19. The film formation apparatus accordingto claim 17, wherein the first chamber includes a first dischargingelectrode and a second discharging electrode; and wherein the secondchamber includes a third discharging electrode and a fourth dischargingelectrode.
 20. The film formation apparatus according to claim 17,wherein the first chamber includes a roller; and wherein the secondchamber includes at least two first discharging electrodes and a seconddischarging electrode.
 21. The film formation apparatus according toclaim 17, wherein the first chamber includes at least two firstdischarging electrodes and a second discharging electrode; and whereinthe second chamber includes at least two third discharging electrodesand a fourth discharging electrode.